Conversely, in 2013 the individual prisoners in receipt of benefits received an average of £1787, three times more than previous years.

But £21m still hasn’t been recouped by DWP. From 2007 to 2011, it had only made losses.

We also found that DSDNI has paid prisoners £1.94 million in benefits over the last six years, despite not being entitled to them.

The data obtained from the FOI requests weren’t very clear either in terms of data analysis or language used.

We had to clean and enter the data manually for it to be analysed – here is the data in the correct format for DWP:

The data for overpayments paid to prisoners by DSDNI:

By simply entering the data in a clear way into a spreadsheet, we were able to see year-on-year changes and perform further calculations such as how much each prisoner received on average.

One thing remained unclear still; the meaning of the headings and the language used by the two departments.

Value of recovery refers to the amount that has been paid back to DWP by prisoners,

Value of debts means the amount of benefits paid to prisoners throughout the financial year, essentially overpayments.

Volume refers to the number overpayments cases rather individual overpaid prisoners. A prisoner can be counted in more than one financial year if they have received a new overpayment in more than one financial year. The departments weren’t able to tell the exact number of prisoners.

Value recoverable (DSDNI) is amount could be possibly recouped from the prisoner.

Value non-recoverable (DSDNI) means the benefit could not be given back to the department.

However, the data does not include Housing Benefit, because it is administered by Local Authorities rather than DWP. That could provide a follow up story for anyone who wants to dig further. Want to investigate? Get in touch through the comments below.